The answer seems to be, when it's a hat. But it could be, "it's a mystery."
Hi, Jo Beverley here. As Pat said, we got talking about headwear, and I began to wonder when bonnets, in the way we usually think about them -- which I assume is as in the picture at the left -- came into being.
Was the brimmed bonnet a 19th century invention? My experience is that in the mid 18th century at least, people spoke of hats, and they didn't have anything that tied beneath the chin. As in the picture at the right. I know we have some costume experts here, so perhaps someone can expand on what I found out.
The Oxford English Dictionary has this general definition of "bonnet" which is, A head-dress of women out of doors; distinguished from a hat (at present) mainly by the want of a brim, and by its covering no part of the forehead.
It's a bit unsatisfactory. The "want of the brim" implies that in the earlier examples below the bonnet is what's sometimes called a Scotch bonnet, ie, more like a beret. The "out of doors" doesn't cover the many occasions when a bonnet is a soft, indoor head covering. But here we have these examples of usage.
1499 Acct. in Comm.-place Bk. 15th C. (1886) 167 It. for a bonet of welwete bowte for hyr at Norweche.
?a1513 W. Dunbar Poems (1998) 149 Pryd, With bair wyld bak and bonet on syd.
1530 Papers Earls of Cumbld. in Whitaker Hist. Craven 305 Three black velvet bonnetts for women.
1716 S. Masters Brit. Patent 403 A new way of working and staining in straw and..adorning hatts and bonnetts.
1786 Lounger No. 79 The progress of bonnets from the quaker to the Shepherdess and Kitty Fisher, and thence to the Werter, the Lunardi, and Parachute.
I tried looking up these bonnets and found nothing except for the Lunardi. Lunardi was a famous balloonist, and this was named for him. "(balloon-shaped and standing some 600 mm tall)" according to Wikipedia. 600 mm is about 2 feet. More here. However, I would say the Lounger, a periodical, was referring to items we would think of as bonnets, though I'm not sure any had brims and ribbons.
By 1881 R. G. White Eng. Without & Within ii. 55 states that "A bonnet has strings, I believe, and a hat has not." That "I believe" suggests confusion, and it's hardly surprising.
I consulted La Belle Assemblee. There are a lot of them available on googlebooks here. Unfortunately many seem to be missing their fashion plates.
They don't provide much clarity. Take this explanation of a plate. It calls this confection a hat, but it has ribbons. It does, however, lack a brim. What are we to conclude -- other than that ladies were encouraged to dress extremely distractingly for the opera?
A description from an 1815 edition of LBA on Parisian style is particularly confusing, especially as there is no illustration to go with it.
Of course, once Napoleon was done for, Paris and Parisian fashion was the latest thing, so this would have been read with great attention. As a character in The Viscount Needs a Wife remarks, France is the old enemy and Britain had just emerged from a long war with them, but everyone is rushing over to Paris to learn the latest styles.
"As the French ladies study, with the most careful precision, that laudable part of coquetry which teaches them to adopt those fashions which are best suited to set off their persons, so it is not to be wondered at that they pay particular attention to the most lovely and exalted part of the human form, the head.
Here the various caprices of taste and fancy are most eminently displayed; here the Parisian beauty attracts the eye, as she sometimes spurts a hat of cloth, of the same colour as her pelisse; another challenges admiration, and sometimes envy, by a scarce and costly article, a hat of Chinese velvet, stamped in clouds, or of a snow-like whiteness: scarce has the passer-by regarded this elegant fair one, than another whimsical worshipper of fashion darts on his sight, in a black velvet hat spotted with rose colour, surmounted by plumes of black feathers: the next, in a hat of simple black velvet, a belle blonde, adds thereby to the dazzling fairness of her complexion; another, with much intelligence marked in her fine blue eye, attracts the general admiration by a late new fashioued bonnet of the helmet kind, called the Spartan bonnet; while another presents herself in a large black chip or straw bonnet, leaning on her friend, who wears a hat of silk shag, turned up on each side. The crowns of the hats lower visibly every day, and one kind of bonnet seems to be prevalent at the museums and at morning lounges; it is of cloth with a very flat crown, and is ornamented with gold lace."
It probably all made perfect sense to the English lady studying this news, but it befuddles me.
It's not helped by the fact that most ladies had portraits set indoors, so there aren't many head-coverings on view there other than frilly lace caps. Let's not get into the word cap!
This portrait, which is one of my favorites, bucks the trend, and the Georgian lady has a very stylish hat. I've always liked it for Rothgar's half-sister Hilda, and her down-to-earth husband, Lord Steen, enjoying their country life away from the dramas of London. There's more about the Georgian Malloren family here.
I think I'll stick to my practice of calling a hat something that sits on the head without ribbons beneath the chin, and a bonnet something that has such ribbons.
Here are a couple more. A Regency bonnet, I think, and a Georgian hat. I think this lady is very proud of her headwear!
What do you think?
I'll give a copy of Too Dangerous for a Lady to one commenter here, so have your say. Another question. When did you last see a hat or bonnet on the cover of a romance?
Jo